为什么下面的代码输出的结果 a, b是orange, c是green呢？



data test;
        a = "x123";
        b = " X123";
        c = 1;
run;
ods listing close;                                       
ods tagsets.ExcelXP
    file = "\\cnbej-vsfs02\data1\Users\q823268\test_&sysdate9..xml"
    style=sasweb;

ods tagsets.ExcelXP options(sheet_name='test' orientation='landscape' embedded_titles='yes'
        autofit_height='yes' Frozen_Headers='9' row_repeat='1-9' AutoFilter='All' FitToPage='yes'
        Pages_FitWidth='1' Pages_FitHeight='300' zoom='70' absolute_column_width='17');
proc report data=test nowd headline headskip missing spacing=5 split='*';

        Columns  a b c;
        Define a        / Display;
        Define b        / Display;
        Define c        / Display;

        Compute a;
                if c = 1 then call define(_COL_,"style","style=[background=green foreground=white]");
                else call define(_COL_,"style","style=[background=orange]");
        Endcomp;
        Compute b;
                if c = 1 then call define(_COL_,"style","style=[background=green foreground=white]");
                else call define(_COL_,"style","style=[background=orange]");
        Endcomp;
        Compute c;
                if c = 1 then call define(_COL_,"style","style=[background=green foreground=white]");
                else call define(_COL_,"style","style=[background=orange]");
        Endcomp;
Run;
ods tagsets.ExcelXP close;
ods listing;